May 26, 1916] 



SCIENCE 



753 



water. Studies carried out by means of emul- 

 sions of oil and water are altogether too crude 

 to determine the exact ratios in which antag- 

 onistic electrolytes exert compensatory effects. 

 After experimenting with various procedures 

 the following method was finally adopted. 

 Aqueous solutions containing NaOH or IsTa 

 oleate were allowed to run from a Traube 

 stalagmometer or capillary pipette through 

 oliYe oil containing a certain amount of fatty 

 acid. If solutions of suitable strength were 

 employed, surface films of soap were produced 

 at the interface between oil and water, when 

 the aqueous solution flowed out of the orifice 

 of the pipette and came in contact with the 

 STorrounding oil. The size of an individual 

 drop formed, and, since the volume is con- 

 stant, its inverse the number of drops, de- 

 pended upon the concentration of the NaOH 

 employed. A Jlf/1,000 NaOH solution gave 

 from 40 to 45 drops, while one of half this 

 strength gave from 20 to 25 drops, and one of 

 double the strength gave several hundred drops 

 or ran through the oil in a stream without the 

 formation of any drops whatever. If NaCl 

 was added to a given system of this type, the 

 number of drops was rapidly increased, as will 

 be seen from the accompanying table. If 

 CaCL, was added to such a system the number 

 of drops was diminished, but when NaCl and 

 CaClj were employed together they appeared 

 to exert a compensatory effect upon one an- 

 other in the proportions of 100 molecules of 

 INTaCl to one or two molecules of CaCl,, ac- 

 cording to the concentration of the solution 

 employed. (See table.) 



To avoid any possibility of confusion, or 

 any idea that this antagonism between CaCl, 

 and l^aCl is due to an antagonism between Ca 



and Na, the writer wishes to emphasize par- 

 ticularly the fact that these antagonistic effects 

 are always attributable to a balance between 

 cations, on the one hand, and anions, on the 

 other, adsorbed on or reacting with a surface 

 film or membrane. It simply happens that, in 

 the case of CaCh, the cation Ca is far more 

 readily adsorbed than the anion CI, while, in 

 the case of ITaCl, the anion CI is somewhat 

 more readily adsorbed than the cation iN'a. 

 The effect obtained from each individual salt 

 is a resultant of the relative adsorption of 

 cation and anion ; and the effect obtained from 

 an admixture of two or more salts is the re- 

 sultant of the relative adsorption effects 

 exerted by all the cations and anions involved. 

 It will be seen therefore that, while CaCl, 

 exerts an effect like an acid on account of its 

 dominant cation, ITaCl exerts an effect like 

 an alkali on account of its dominant anion. 



The remarkable correspondence between the 

 ratios in which ISTaCl and CaClj balance one 

 another in these purely physical systems and 

 in the biological systems referred to above led 

 the writer to investigate further the relations 

 exhibited by a variety of electrolytes known 

 to exert antagonistic effects in biological sys- 

 tems. In several hundred experiments, full de- 

 tails regarding which will shortly be pub- 

 lished, the writer has been able to duplicate 

 the results obtained by Loeb, Osterhout, Lillie 

 and numerous other biologists, on living cells. 

 The ratios and proportions in which sub- 

 stances having a dominant cation antagonize 

 substances having a dominant anion are ap- 

 proximately the same in the great majority 

 of comparable physical and biological experi- 

 ments. For convenience in describing experi- 

 ments those substances having a dominant 

 cation, which diminish the dispersion of the 

 film in water, thus rendering the system less 

 permeable to water, are termed " protective," 

 those having a dominant anion, which increase 

 the dispersion of the film in water, thus ren- 

 dering the system more permeable to water, are 

 termed " destructive." Even those substances 

 like salts of Mg, and certain non-electrolytes, 

 the anesthetics, which exhibit abnormalities in 

 biological systems, functioning under varying 



